Leaf springs as used in vehicles comprise a generally curved central section and end sections having openings or eyes to receive connectors for attaching the spring to the vehicle. Leaf springs have been constructed of fiber reinforced plastic material in order to reduce the overall weight of the vehicle. In certain leaf springs of this type, the central section is molded from longitudinally extending fibrous material impregnated with a thermosetting resin and separate metal end sections are attached through mechanical connectors to the end of the central section.
In other fiber reinforced plastic leaf springs, continuous strands of fibrous material impregnated with a thermosetting resin are wound around spaced tubular bushings in a loop configurations. The wound structure is then placed in a mold with the parallel runs of the loop configuration being brought together in flatwise contiguous relation. Subsequently, the resin is cured to provide an integral structure. With a spring of this type, the strands extend around the bushings and join the curved central section of the spring at neck areas. In service, when a load is applied to the end portions of the spring, the strands have a tendency to delaminate along the neutral axis at the neck areas. In addition, torsional load applied to the springs on turning of the vehicle, or torsional stress resulting from independent wheel suspension, also has a tendency to delaminate the strands at the neutral axis adjacent the neck area.
To prevent this delamination it has been proposed to add clamps or other fasteners at the vulnerable neck area, but the addition of these fasteners normally requires holes or other openings to be formed in the spring which severs the longitudinally extending reinforcing strands and correspondingly reduces the physical characteristics of the spring.